Method of covering a glass wall portion of a cathode-ray tube



1966 J.SPRENGERS ETAL METHOD OF COVERING A GLASS WALL PORTION OF A CATHODE-RAY TUBE Filed April 22, 1963 FIG-.2

R m an B Mm T NMN N m w Z 6 EMS Jfi m m Mm P ma} United States Patent 3,293,098 METHOD OF COVERING A GLASS WALL PORTION OF A CATHODE-RAY TUBE Johannes Sprengers, Christiaan Franciscns Stauttener, and

Cornelis Hendrik van Glabbeek, Emmasingel, Eindhoven, Netherlands, assignors to North American Philips Company, Inc., New York, N.Y., a corporation of Delaware Filed Apr. 22, 1963, Ser. No. 274,508 Claims priority, application Netherlands, Apr. 26, 1962, 277,711 7 Claims. (Cl. 156-245) Our invention relates to a method of covering that portion of the glass wall of a cathode-ray tube, more particularly, a television display tube, which adjoins the end window with an implosion-resistant layer which also serves as a frame for the window.

In US. applications Serial No. 143,893, filed October 9, 1961, now US. Patent No. 3,166,211 and Serial No. 154,611, filed November 24, 1961, now US. Patent No. 3,206,056, it has been suggested to cover at least the portion of the wall of a cathode-ray tube which adjoins the picture field with a layer of synthetic material containing fibres. Such an armoured layer was provided by simultaneously spraying fibres and hardening synthetic material onto the bulb, the layer subsequently being pressed against the bulb by means of a roller.

It is an object of our invention to improve this method in which it has been found difficult for the edge of the armoured layer surrounding the picture field to be finished smoothly.

Further objects of the invention will appear as the specification progresses.

According to the invention, the layer containing the armour and at least that portion of the layer which constitutes a frame for the picture field and which extends over the portion of the wall adjoining the picture field, is first formed into an annular shaped body. This body is then placed in an annular matrix of a shape similar to that of the portion of the wall to be covered so that it can slide over a cylindrical central part of a crosssectional area similar to the shape of the window end of the tube. Thereafter, a hardenable material is poured in the liquid state onto the annular-shaped body of armour in the matrix, and subsequently, the matrix is moved towards the tube, whereby the annular-shaped body of armour is pushed against the tube wall and the hardenable material is pressed upwards through the armour up to the upper edge of the matrix. The hardening material then is allowed to harden. To facilitate removal of the matrix, it is preferably first covered with .a thin layer of a material, for example, a silicone resin, paraffin, oil or the like, or a pulverulent material, to which the hardenable material does not adhere.

As armour, use may be made of fibres or textures of materials which can strengthen the layer of synthetic material sufficiently to prevent a crack in the glass from extending further. Glass fibres of the order of a few centimetres in length have been found very suitable as an armour. However, a metal gauze, glass or synthetic materials, may be used as well.

The envelope of the tube may advantageously be provided previously with a layer of hard glass which may be subject to compressive stress, thus permitting the use of glass of a smaller wall thickness.

The invention will now be described in detail with reference to the accompanying drawing, in which:

FIG. 1 is a sectional view of a matrix as used in the method according to the invention, and

FIG. 2 is a sectional view of a pre-formed annular armour.

, ICC

In FIG, 1, a cathode-ray tube for television picture display purposes, which is otherwise entirely finished and comprises a neck 1, a glass cone 2 and a window 3, is maintained pushed by means of a vacuum suction-piece 4 on a cylindrical part 5 with the interposition of a sealing ring 6, for example of rubber. The part 5 is surrounded by an annular matrix 7 which can slide up and down along it. The left portion of FIG. 1, designated A, showsthe position of the hollow annular matrix 7 in which the pre-formed annular-shaped body of armour material 8 (see also FIG. 2), for example glass-fibres held together by means of a binder, such as polyvinyl alcohol, may be placed in the matrix. Then an exactly proportioned amount of hardenable material 9, preferably synthetic material, is poured into the matrix. The matrix 7 may be constituted of metal or synthetic material. The matrix is then pushed upwards by means of rods 11 into the position shown in the right side of FIG. 1 designated B in which the annular-shaped body of armour 8 is pushed against the portion of the window 3 which adjoins the window. Since the annular-shaped body of armour in position 8' also engages the sealing ring 6, a smooth boundary of the edge of the armour is obtained. When the matrix 7 is pushed upwards, the liquid 9 is pressed through the armour between the matrix and the envelope of the tube. The amount of liquid 9 is chosen so that it reaches exactly the upper edge of the matrix 7 in position 7 thereof. Preferably, the cone 2 of the cathode-ray tube has previously been provided with a protective layer consisting, for example of an armoured layer 10 of synthetic material, which now merges into a layer 8' adjoining the picture field, while the glass wall may previously be covered with a glue layer of polyvinyl acetate.

However, as an alternative, the cone may previously be covered with a cup, preferably made of metal, it then being possible to fill the space between this cup and the glass with a hardenable material in a state such that it can be poured in this space. The metal cup is preferably provided with lugs for securing the tube in a receiver cabinet.

In other cases provisions will be made in the matrix 7 to ensure that the attachment lugs are accommodated in the armoured layer 8.

After synthetic material 9 has hardened, the matrix 7 is pushed downwards again, and after the vacuum in the suction piece 4 has been eliminated, the tube may be removed. The edge of the armour 8', impregnated with the hardened material, which surrounds the window and may serve as a mask, is entirely smooth and needs no special after-treatment.

It has been found that by the method described, complete impregnation of the armour with the hardenable material is obtained in a rapid manner, in contrast to the methods in which the material is poured, sprayed or smeared on the armour and in which the impregnation of the armour with this material is much more laborious and takes considerably longer.

The armour may consist of any materials which are suficiently strong, such as metal gauze, braided metal wire, glass or synthetic material. Besides, any hardenable material that can yield a sufficiently adhering and strong layer with the armour is usable, for example concrete.

Furthermore, instead of using the layer which has to prevent the hardenable material from adhering to the matrix 7, a thin cup of, for example, metal or synthetic material could be used and serve afterwards as a smooth covering layer for the implosion-resistant layer 8.

In conclusion, it is possible to place the armour in the matrix 7 in the form of a flat ring. When the matrix 7 is moved upwards, the flat ring then readily acquires the correct shape due to its being pushed against the tube wall. 7

While we have described the invention with reference to specific embodiments and applications thereof, other modifications will be apparent to those skilled in the art without departing from the spirit and scope of the invention.

What we claim is: 1. A method of covering a portion of a glass wall of a cathode-ray tube adjoining an end window with an implosion-resistant layer which also serves as a frame for the end window comprising the steps, forming a mate rial which constitutes an armour for the layer into an annular-shaped body, placing the annular-shaped body in an annular matrix having a shape similar to that of the portion of the wall to be covered with an implosionresistant layer, placing the annular matrix containing the annular-shaped body on a cylindrical member having a cross-sectional area similar to that of the end window, interposing' a sealing member between the cylindrical member and the end window, applying in la fluid state a hardenable material onto the annular shaped body in the matrix, moving the matrix on said cylindrical member toward said tube whereby the annular-shaped body covered with hardenable material is pushed against the wall of the tube and the hardenable material pressed through the annular-shaped body to the upper edge of the matrix, and allowing the hardenable material to harden before removing the matrix.

2. A method as claimed in claim 1 in which the material constituting the armour of the implosion-resistant layer consists of glass fibers of the order of centimeters in length.

3. A method as claimed in claim 1 in which the material constituting the armour of the implosion-resistant layer is a braided metal wire.

4. A method as claimed in claim 1 in which the hardenable material is a synthetic material.

5. A method as claimed in claim 1 in which the hardenable material is concrete.

6. A method as claimed in claim 1 in which a cupshaped annular member is first inserted into the annular matrix before the annular-shaped body, the cup-shaped annular member thereafter serving as a covering layer for the implosion-resistant layer.

7. A method as claimed in claim 1 in which a covering layer is first applied over a portion of the tube adjoining that portion which is to be covered with the implosionresistant layer.

References Cited by the Examiner UNITED STATES PATENTS 2,293,529 8/ 1942 Bedford 1787.85 2,828,799 4/1958 Harrison 156-84 3,007,833 11/1961 l'ackman 156213 X 3,013,117 12/1961 Nichol 1787.82 3,028,284 4/1962 Reeves 156213 X 3,075,870 l/1963 Hedler et al 166--295 3,200,188 8/1965 Lange et al. 220-21 X EARL M. BERGERT, Primary Examiner.

HAROLD ANSHER, Assistant Examiner. 

1. A METHOD OF COVERING A PORTION OF A GLASS WALL OF A CATHODE-RAY TUBE ADJOINING AN END WINDOW WITH AN IMPLOSION-RESISTANT LAYER WHICH ALSO SERVE AS A FRAME FOR THE END WINDOW COMPRISING THE STEPS, FORMING A MATERAIL WHICH CONSTITUTES AN ARMOUR FOR THE LAYER INTO AN ANNULAR-SHAPED BODY, PLACING THE ANNULAR-SHAPED BODY IN AN ANNULAR MATRIX HAVING A SHAPE SIMILAR TO THAT OF THE PORTION OF THE WALL TO BE COVERED WITH AN IMPLOSIONRESISTANT LAYER, PLACING THE ANNULAR MATRIX CONTAINING THE ANNULAR-SHAPED BODY ON A CYLINDRICAL MEMBER HAVING A CROSS-SECTIONAL AREA SIMILAR TO THAT OF THE END WINDOW, INTERPOSING A SEALING MEMBER BETWEEN THE CYLINDRICAL MEMBER AND THE END WINDOW, APPLYING IN A FLUID STATE A HARDENABLE MATERIAL ONTO THE ANNULAR SHAPED BODY IN THE MATRIX, MOVING THE MATRIX ON SAID CYLINDRICAL MEMBER TOWARD SAID TUBE WHEREBY THE ANNULAR-SHAPED BODY COVERED WITH HARDENABLE MATERIAL IS PUSHED AGAINST THE WALL OF THE TUBE AND THE HARDENABLE MATERIAL PRESSED THROUGH THE ANNULAR-SHAPED BODY TO THE UPPER OF THE MATRIX, AND ALLOWING THE HARDENABLE MATERIAL TO HARDEN BEFORE REMOVING THE MATRIX. 